Problem: $ { \left[\begin{array}{rr}{2} & {-1} \\ {3} & {1}\end{array}\right]-\left[\begin{array}{rr}{2} & {3} \\ {3} & {3}\end{array}\right] = {?} } $
Answer: To find the difference of two matrices, subtract the corresponding items between each matrix. ${\left[\begin{array}{rr}{2}-{2} & {-1}-{3} \\ {3}-{3} & {1}-{3}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{0} & {-4} \\ {0} & {-2}\end{array}\right]}$